# static-arena

A bump-pointer arena whose buffer lives entirely on the stack (or in `static mut` storage). Zero `malloc`, zero `free`, so it composes with the `#[no_alloc]` real-time contract.

Because C+ does not yet have const-generic struct parameters, it ships two fixed shapes: `StaticArena16K` (16 KiB) and `StaticArena64K` (64 KiB). The 16K shape has the full surface (`alloc_bytes`, `alloc_bytes_aligned`, `alloc_zeroed_bytes`, `alloc_str`, `reset`); the 64K shape is the same minus `alloc_str` and `alloc_zeroed_bytes`.

```cplus
import "static-arena/static-arena" as sa;

let mut a: sa::StaticArena16K = sa::StaticArena16K::new();
guard let option::Option::Some(p) = a.alloc_bytes_aligned(64 as usize, 8 as usize) else {
    return 1;   // OOM
};
// ... use p ...
a.reset();      // recover full capacity, reuse
```

The stack size ceiling is roughly 128 KiB; for larger arenas, allocate in `static mut` and reference by pointer, or use the heap-backed [arena](/docs/packages/arena).